H.323 user, service and service provider mobility framework for the multimedia intelligent networking

ABSTRACT

The present invention provides a method and system for assuring H.323 alias address portability to an H.323 user in real-time H.323 multimedia communications where the H.323 user is registered with a home gatekeeper for the home zone of the H.323 user. Alias address portability may be obtained using a central database that is known to the administrative zones and is used for alias address mapping, or alternatively, may be obtained by using a distributed database. The method may be implemented by: sending, by the H.323 user, a message with a called H.323 entity&#39;s alias address, to the home gatekeeper to originate a call to the called H.323 entity; confirming that the alias address, services, and service providers are portable; converting the alias address to a called routable alias address for the called H.323 entity and sending the alias address to the H.323 user; and placing the call to the called H.323 entity.

RELATED APPLICATIONS

This application is a continuation of, claims priority to, andincorporates by reference herein in its entirety U.S. patent applicationSer. No. 10/835,632, now U.S. Pat. No. 7,317,701, filed 30 Apr. 2004,which is a continuation of U.S. patent application Ser. No. 09/642,980,now U.S. Pat. No. 7,346,022, filed 18 Aug. 2000, which claims thebenefit of U.S. Provisional Applications 60/156,363 and 60/156,482,filed on 28 Sep. 1999, by Radhika R. Roy, which are hereby entirelyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to audio and video conferencingservices, and more particularly to coupling home/small businessnetwork-based devices using Internet Protocol (IP) techniques to provideaudio and/or video conferencing services using a wide area network-basedintelligent service controller.

BACKGROUND OF THE INVENTION

H.323 is an International Telecommunications Union (ITU) standard thatprovides a foundation for audio, video, and data communications acrosspacket-based networks, including the Internet. Compliance with the H.323standard permits interoperability, allowing users to communicate withoutconcern about non-compatibility. The H.323 recommendation provides astandard for multimedia communications over packet switched networks .Such networks include many corporate networks, packet-switched TCP/IPnetworks, IPX over Ethernet, Fast Ethernet and Token Ring technologies,public Internet, ATM networks, and/or others. H.323 enablesvideoconferencing as well as addressing call control, multimediamanagement, and bandwidth management. Thus, H.323 encompassesinter-network multipoint conferencing among terminals that support notonly audio, but also video and data communication.

Use of multimedia communications over packet-based networks hasincreased as an alternative form of communication due in part to theexpense of the use of public-switched telephone networks(PSTN)/integrated services digital networks (ISDN). However, thepacket-switched traffic can also be sent over the circuit-switched PSTNnetwork (e.g., IP-over-PPP-over-PSTN or IP-over-PPP-ISDN), and H.323packet bitstreams can be sent over them. Rapid expansion of packet-basednetworks has made the need for interoperable equipment and systems moreurgent. While the H.323 has addressed terminal mobility, it has notprovided a user, service and service provider mobility framework, whichis needed for both the wired and wireless environment.

SUMMARY OF THE INVENTION

The present invention provides an H.323 user, service and serviceprovider mobility framework for implementing H.323 alias addressportability in real-time H.323 multimedia communications. The H.323 useris registered with a home gatekeeper for the H.323's home zone. Aliasaddress portability may be obtained using a central database that isknown to the administrative zones and is used for alias address mapping,or alternatively, may be obtained by using a distributed database. Themethod may be implemented by: sending, by the H.323 user, a message witha called H.323 entity's alias address, to the home gatekeeper tooriginate a call to the called H.323 entity; confirming that the aliasaddress is portable; converting the alias address to a called routablealias address for the called H.323 entity and sending the alias addressto the H.323 user; and placing the call to the called H.323 entity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is one embodiment of a zone, gatekeeper and home/visitor databasearchitecture in accordance with the present invention.

FIG. 2 is one embodiment of gatekeepers and zones with a centralizedhome location database architecture in accordance with the presentinvention.

FIG. 3 is one embodiment of a method of providing alias addressportability using a decentralized database in accordance with thepresent invention.

FIG. 4 is one embodiment of a method of providing alias addressportability using a distributed database in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unlike terminal mobility, user mobility and service mobility are equallyapplicable for both the wired and the wireless environment because thehandover during the terminal mobility is only possible in the wirelessenvironment. Real-time H.323 multimedia communications services such asaudio, video and/or data require a multimedia intelligent networkingplatform when the mobility of users, services such as H.450.x (i.e.,supplementary services: multimedia call forwarding, multimedia calltransfer, etc) and service providers are addressed. User, service, andservice provider portability require a new kind of multimediaintelligent networking in the context of H.323.

User mobility is defined as the ability for a user to maintain the sameuser identity on different terminals or terminal types. In H.323, therecan be many user identities such as alias addresses E.164, TransportAddress, H323ID, URL-ID, Email-ID, Party Number, and the like, that auser can identify. In addition, more aliases such as IMEI, IMSI, andTMSI have also been proposed.

User mobility is defined as an ability of a user to access H.323services at any terminal, i.e., maintaining the same user identity ondifferent terminals or terminal types, and the capability of the H.323system is an ability to provide the H.323 services according to theuser's subscription. User mobility also allows the user to register onany terminal for incoming and outgoing calls.

Thus, user mobility and terminal mobility are independent of each other.An H.323 user may have a sequence of optional alias addresses:

-   -   E.164    -   IMEI    -   IMSI    -   TMSI    -   URL-ID    -   Email-ID    -   Party Number    -   Personal ID    -   Transport Address

For example, E.164 may be the first item that a user may like to keepthe same on different terminals. The E.164 number portability in H.323is almost the same local number portability (LNP) issue as in theintelligent network (IN). Again, LNP is also related to the servicemobility, service provider mobility, and location (geographic) mobility(beyond or outside a rate center).

Similarly, with the present invention, other user identities may be keptthe same. In each case, there will be a different implication in thenetworking.

In addition, an endpoint that a user is usually identified with willalso have a call signaling or transport address and a RAS address. Anendpoint may also use different transport or network addresses fordifferent channels (e.g., audio, video, and/or data) within the samecall. The basic assumption is that the call signaling address and theRAS address are not considered to be fixed while considering the H.323user mobility. By same token, the transport or network address that canbe used as an alias address by a user's endpoint is not considered tokept fixed for the user mobility.

In summary, the following can be noted in the context of the usermobility:

-   -   Selected candidate H.323 alias addresses may be kept fixed for        user mobility such as, for example: E.164, IMEI, IMSI, and/or        TMSI, URL-ID, Email-ID, and/or party number.    -   Personal Ids may be utilized.    -   No transport or network address either for the endpoint alias or        for the call signaling address or RAS address is kept fixed.    -   As an example, E.164 may be kept fixed for the user mobility,        and may be used to show the impact of the user mobility in the        context of H.323 multimedia communications.    -    Then, the other alias addresses may be considered to analyze        the impact on the user mobility.

Service mobility is defined as the ability for a user to obtain aparticular service independent of user and terminal mobility. That is,the foreign network must have the means to obtain the parametersrequired for the service.

Service mobility means that the user may have the same H.323 services(e.g., H.450.x supplementary services such as multimedia callforwarding, multimedia call transfer, etc.), may keep the same useridentity (user mobility), or may use the same terminal (terminalmobility) as the user moves from its home network to a foreign one.Service mobility may also imply that the user may use the same useridentity (user mobility) or the same terminal (terminal mobility) afterchanging H.323 service providers. As used herein, service mobility isdiscussed in the context of user mobility only.

Service provider mobility is defined as the ability for a user tomaintain the same user identity on different terminals or terminal typesafter changing the service providers. The network or networks that carryan H.323 multimedia call may have more multiple carriers. The usermobility implies that the alias address or addresses are portable. Forexample, for the E.164 address, there must be a mechanism that providesfor the portable E.164 address to be mapped over the physicalpacket-based network for actual routing of the call.

The mapping function of the E.164 address to an actual routable call inH.323 may be similar to the local routing number (LRN) method in the IN.In fact, the service provider portability in H.323 may be achieved usinga method similar to IN's LRN. However, using such a method has severeimplications on the H.323 networking because a significant amount ofanalysis is needed to understand how the service provider portabilitycan be accomplished. There are many ways H.323 multimedia (audio, video,and/or data) services (e.g., H.450.x) may be offered by the serviceproviders with the user mobility. This user, service, and serviceprovider mobility is termed “multimedia intelligent networking”.

H.323 uses alias addresses for endpoints. Such alias addresses are usedto identify users. More alias addresses such as IMEI, IMSI, TMSI, andpersonal ID have also been proposed. In the case of mobile users, one ormore of the alias addresses may be fixed while the users move from oneplace to another. In the present invention, the H.323 users, likeendpoints, are also associated with the H.323 alias addresses. In thepresent invention, if a user wants to keep the same identity whilemoving from place to place, the following objectives are needed tomaintain both service and service provider mobility:

-   -   Alias address portability supports the H.323 services (e.g.,        H.450.x), features, and capabilities without degradation in        service quality and network reliability below a predetermined        level.    -   The implementation of the alias address portability is done very        efficiently without requiring subscribers to change their alias        addresses.    -   A service provider routes the H.323 multimedia (audio, video,        and/or data) call to customers without being affected by the        networks of other carriers when the alias address portability is        implemented.

In H.323, the alias addresses have been described as:

An endpoint may also have one or more alias addresses associated withit. An alias address may represent the endpoint or it may representconferences that the endpoint is hosting. The alias addresses provide analternate method of addressing the endpoint. These addresses includeE.164 or partyNumber addresses (network access number, telephone number,etc.), H.323 IDs (alphanumeric strings representing names, e-mail-likeaddresses, etc.), and any others defined in Recommendation H.225.0.Alias addresses are unique within a Zone, Domain, among Zones, and amongDomains. Gatekeepers, MCs, and MPs do not have alias addresses.

When there is no Gatekeeper in the system, the calling endpointaddresses the called endpoint directly using the Call Signaling ChannelTransport Address of the called endpoint. When there is a Gatekeeper inthe system, the Gatekeeper translates the called endpoint into its CallSignaling Channel Transport Address or alias address. The calledendpoint's E.164 address may consist of an optional access code followedby the E.164 address. The access code consists of n digits from the setof 0 to 9, * and #, where n is a predetermined number whose number ofdigits and their meaning is left to the discretion of the manufacturer.One purpose of such an access code might be to request access to aGateway. The Gatekeeper may alter this address prior to sending it tothe destination.

The H.323 ID consists of a string of ISO/IEC 10646-1 characters asdefined in Recommendation H.225.0. It may be a user name, conferencename, e-mail name, or other identifier. An endpoint may have more thanone alias address, including more than one of the same type, which istranslated to the same Transport Address. The endpoint's alias addressesare unique within a Zone. In this embodiment, the call signalingtransport or network address and the RAS transport or network addressare not kept fixed in the context of the user mobility.

In H.323, the called endpoint's E.164 address may consist of an optionalaccess code followed by the E.164 address. E.164 provides a 10-digittelephone number of format NPA-XXX-XXXX. In this format, Number PlanArea (NPA) may be a geometric information code (GIC) or a service accesscode (SAC). The last seven digits usually represents a subscriber numberin the NXXXXXX where N is a number between 2 and 9, and X is a numberbetween 0 and 9. In this subscriber number format, the first threedigits (i.e., NXX) are typically a central office (CO) code thatidentifies the CO switch of the telephone number. There may also be somesubcategories in the NPA code such as geographic NPA (G-NPA) (e.g., areacodes) and non-geographic NPA (NG-NPA) (e.g., 800-number, 900-number,mobile user numbers.

Thus, the H.323 communications system deals with the packet-basednetwork (PBN). In this context, an E.164 number used by a user orendpoint may be considered to have a kind of non-geographicsignificance. Such is also the case with respect to user mobility wherean H.323 user wants to keep the same identity even if the user movesfrom one place to another.

H.323 deals with the multimedia (audio, video, and/or data) calls. Acall may be point-to-point, point-to-multipoint, ormultipoint-to-multipoint. The call-processing intelligence may becentralized as well as distributed over the packet-based networks (e.g.,IP, ATM). The user, service, and service provider mobility requires thatthe alias addresses be portable and be kept fixed while users roam fromplace to place. Consequently, these portable addresses will have nogeographical significance with respect to the packet-based networks.Such networking is termed as multimedia intelligent networking (MIN) inthe context of H.323. In other words, multimedia intelligent networkingadds multimedia (audio, video, and/or data) service capabilities to thepacket-based networks, which are independent of the involved packetswitches (e.g., IP routers, ATM switches).

With MIN, service providers can rapidly and flexibly provisionmultimedia services to customers. What makes MIN so powerful is thatmultimedia services may be deployed on centralized or distributeddatabases across the network based on cost-performance trade-offs. Asshown in FIG. 1, in H.323, each mobile entity needs to register with itshome gatekeeper GK1 102, GK2 104, GK3 106. The mobile entity designatesits home GK, which becomes the central controlling point to manage itsmobility. Each mobile entity has a home/foreign zone 108, 110, 112, 114.Even if a mobile moves to a foreign zone, it needs to register with aforeign GK. As result, a GK needs to manage the location information forboth home and foreign visitors. A GK has databases 116, 118, 120 forkeeping location information for both home and visitor or foreignlocations. The terminology “foreign” and “visitor” are usedinterchangeably herein. Hence, like the GK architecture, thehome/visitor architecture is also distributive.

With respect to terminal mobility, both distributed and centralizeddatabases may be used to manage the location as the user moves with itsterminal from one place to another. In H.323, each mobile entity needsto register with its home GK. The mobile entity designates its home GK,which becomes the central controlling point to manage its mobility. Evenif a mobile moves to a foreign zone, it needs to register with a foreignGK. As a result, a GK needs to manage the location information for bothhome and foreign visitors. Thus, each GK has and maintains databases forhome and visitor location information. FIG. 1 shows one embodiment ofzones, GKs and home/visitor databases architecture in accordance withthe present invention.

However, in H.323, the services between the GK and the location databaseare known as the backend services and the protocol between thesefunctional entities is known as the backend services protocol. Since thebackend services and the protocol have not yet been standardized inH.323, any known backend service and protocol technique may be used.

Location management involves the updating of location databases whencurrent location information is available. During the callestablishment, these databases are queried to determine the currentlocation of the mobile entity. Such querying may be costly, especiallywhen the mobile entity is located far away from its assigned home GK.So, the location management may need to be further optimized. In oneembodiment, the location of the home location information may becentralized to optimize location management.

As shown in FIG. 2, in this centralized home location databasearchitecture, the management is generally simpler because the homelocation of a mobile entity remains the same, and this information maybe kept in a central database 202. However, the scalability of such asolution may be problematic, especially in the context of thelarge-scale IP network or the public Internet. There may also behierarchical databases for managing the location information. The choiceof using a distributive location management database vs. using acentralized location management database is a matter of choice ofimplementation. Both embodiments are described below.

For user, service, and service provider mobility, the followingassumptions are made to simplify the analysis:

-   -   Every administrative domain has a single zone.    -   An E.164 alias address assigned to an H.323 user is kept fixed        as the user moves from one place to another.    -   Originally, a domain for an alias address (e.g., an E.164        address) assigned to a user in an administrative domain is known        as donor domain.    -   If the alias address is moved from a donor domain due to roaming        of the user, the new domain is called the recipient domain.    -   The moved alias address is referred to as a ported number.

Database methods for alias address portability utilize the alias addressdatabases to route multimedia (audio, video, and/or data) calls to theirdestinations. However a portable H.323 alias address is not a networkroutable number. It needs to be translated to a network address forrouting the call to the destination.

The following describes call scenarios in the case of the centralizeddatabase. As shown in FIG. 3, a central database 302 that is known toall administrative zones may be utilized to provide alias addressmapping. User mobility is implemented using the database. For example, acall is placed by a calling H.323 entity 304 residing in administrativedomain 2 306. The called H.323 entity is a mobile user whose aliasaddress (e.g., E.164 ) remains the same as it moves from place to place.The called mobile user 308 has an alias address assigned from anadministrative domain and has moved to administrative domain 3 310. Upongoing to administrative domain 3, the H.323 user registers with the BEor GK of domain 3, typically in a similar way of registering in the caseof terminal mobility, which is known to those skilled in the art andwill not be described further here. Typically, registration informationhas also been updated in the central database that provides the aliasaddress mapping. The triggering mechanism for updating the database foruser mobility is not defined in the H.323 standard. However, followingthe MIN concept, multimedia call delivery to a ported alias numberconsists of the following steps as shown in FIG. 3:

-   -   Step 1: The calling H.323 party 304 connected to administrative        domain 2 306 wants to place a call to a called party 308. The        calling H.323 party 304 sends a RAS message (usually ARQ) with        the GK 312 of its own domain that contains the called party's        alias address (e.g., 404-457-xxxx (E.164 ]). The details of the        call flow are not shown for simplicity. When the number is        received by the GK/BE 312 of the originating domain 1, the        interaction between the GK/BE 312 and the database 302 occurs.    -   Step 2: The GK/BE 312 of domain 2 306 sends a query to the        database 302 containing the called party's alias address (e.g.,        404-457-xxxx). The database 302 identifies that this alias        address is in the ported address, and a query is launched to the        corresponding alias address portability database of the central        database (a database may be partitioned in many ways: alias        address type, portable alias address, non-portable alias        address, etc.).    -   Step 3: The database 302 maps the ported alias address (e.g.,        404-457-xxxx) to the actual routable network address (e.g., an        IP subnetwork address) in which the mobile user 308 is presently        connected. (If necessary, 404-457xxx may also be mapped to        another E.164 address). The recipient's routable network address        (e.g., IP subnetwork address) is sent back to the GK/BE 312 of        the originating domain 306 with the indication that the called        alias has been the ported number.    -   Step 4: The originating GK or BE 312 sends the resolved routable        network address of the called entity 308 to the calling party        304 (It may happen in the form of an ACF message of H.323). It        may be noted that the called alias number has been the ported        number and does not provide the actual information about the        location of the called party 308. The caller 304 may actually        like to know about the billing rate before placing the call. The        caller 304 may proceed to learn the billing and other related        information before placing the call.    -   Step 5: The caller 304 can now place the call either directly        (Step 5a) or via the GK (Step 5b), knowing the routable address.

In the above scenario, all information of all service providers of alladministrative domains is available in a central database. However, allinformation of all service providers of all administrative domains maynot always be available. Some service providers may keep the databasesseparate. Then the interaction among many databases will be required.The following describes an embodiment wherein the database isdistributed.

In the above embodiment, there was a donor administrative domain thatprovided the user with a ported alias address. If a ported number isdonated by any service provider of any administrative domain, there maybe a mechanism that determines the domain of that service provider. FIG.4 shows this case using the example of E.164 alias addresses.

FIG. 4 illustrates an example wherein an H.323 user 404 is connected toadministrative domain 2 402 and wants to place a call to another user406 whose E.164 alias address is 404-457-xxxx. By knowing the NPA-NXX,it is possible to determine that administrative domain 1 (serviceprovider 1) 408 is the donor of this alias address. So, domain 1 408 isthe domain that has the information on whether this alias address isportable or not. It shows how the alias address is allocated, andwhether information with certain criteria may be distributed amongdifferent databases. In FIG. 4, the following steps may be used in adistributed environment in accordance with the MIN concept:

-   -   Step 1: As in FIG. 3, the calling H.323 party 404 connected to        administrative domain 2 402 wants to place a call to a called        party 406. The calling H.323 party 404 sends a RAS message        (usually ARQ) with the GK of its own domain that will contain        the called alias address (e.g., 404-457-xxxx (E.164 ]). The        detail of the call flow is not shown for simplicity. When the        number is received by the GK or BE 410 of the originating domain        1 402 , the interaction between the GK or BE 410 and the        database 412 occurs.    -   Step 2: The GK or BE of domain 2 402 decides that the alias        address pattern of 404-457-xxxx tells that the administrative        domain 1 (service provider 1) is the donor of this alias address        and sends a query message with the alias address (404-457-xxxx)        to the BE or GK 414 of domain I 408 (usually via H.225.0 Annex        G's accessRequest message) to check whether it is a portable        address or not.    -   Step 3: The GK or BE 414 of domain 1 408 launches a query in its        alias portable checking database to find whether the alias        address (404-457-xxxx) donated by it is portable or not. The        donor domain (administrative domain 1 [service provider 1])        determines that the called alias address has been ported out        after analyzing the database and sends a confirmation message to        the BE or GK 410 of domain 2 402.    -   Step 4: The GK or BE 410 of domain 2 402 sends a query to the        database 412 containing the called alias address (e.g.,        404-457-xxxx). The database 412 identifies that this ported        alias address needs to be mapped to the actual network routable        address (e.g., IP subnetwork address).    -   Step 5: The database 412 maps the ported alias address (e.g.,        404-457-xxxx) to the actual routable network address (e.g., an        IP subnetwork address) in which the mobile user 406 is presently        connected. (if necessary, 404-457xxx may also be mapped to        another E.164 address). The recipient's routable network address        (e.g., IP subnetwork address) is sent back to the originating GK        or BE 410.    -   Step 6: The originating GK or BE 410 sends the resolved routable        network address of the called entity 406 to the calling party        404 (It may happen in the form of an ACF message of H.323). It        may be noted that the called alias number has been the ported        number and does not provide the actual information about the        location of the called party 406. The caller may actually like        to know about the billing rate before placing the call. The        caller 404 may proceed to learn the billing and other related        information before placing the call.    -   Step 7: The calling party 404 may now place the call either        directly (Step 7a) or via the GK (Step 7b), knowing the routable        address.

If the alias address is non-ported, the query to the donor domain savesan unnecessary database query that is needed in the case of thecentralized database case. This results in cost savings. However, if thealias address is a ported number, there may be some issues that need tobe resolved between the donor (original carrier or original serviceprovider) and originator (new carrier or new service provider) relatedto the routing and cost of the call to the customers.

Several scenarios may be considered for the database queries that haveimplications especially when multiple service providers are involved. Ifan H.323 multimedia (audio, video, and/or data) call involves severalservice providers, there can be the following alternatives to triggerthe database query:

-   -   Originating Service Provider Scenario: The originating service        provider may perform the database query in the case of the        originating service provider scenario.    -   Terminating Service Provider Scenario: The terminating service        provider may also perform the database query in the case of the        terminating service provider scenario.    -   “K−1” Scenario: In this situation, the service provider        immediately prior to the terminating service provider performs        the database query.    -   First-GK/BE-that-can-Scenario: For the, the first GK or BE (in        the H.323 call path) that has the database access capability        performs the query.        Each scenario has implications on call routing and billing. The        standards may specify each case with appropriate signaling        mechanisms for queries, and implementations may be made        considering cost-performance trade-offs.

The central database architecture may have scalability problems when thealias addresses portability is deployed nationwide (similar to 800/900databases) or worldwide. A more appropriate solution may be to maintainthe regional databases. Then the issue becomes: Who will maintain thealias addresses portability databases? Will these databases bemaintained by one or more neutral third parties so that the aliasaddresses resources are efficiently made available to new H.323 serviceproviders. In one embodiment, the databases may contain only the portedalias addresses, the associated routable network addresses and serviceprovider information.

In one embodiment, addresses may be cached by the GKs. Similar cachingmechanism may also be applied for the alias addresses portability. Indatabase-based alias addresses portability, it is likely that some ofthe ported alias addresses are frequently accessed from an originatingGK or BE. In that originating GK or BE, one may keep a cache to map thefrequently ported alias addresses to the routable network addresses oftheir recipient GKs or BEs. Thus, the routing information of thefrequently ported alias addresses may be obtained from the cache insteadof the expensive MIN query to the alias addresses portable (AAP)database. The cache approach may be applied using the following steps:

-   -   Step 1: If the RAS signaling message (e.g., ARQ) is sent, the        originating GK or BE checks whether the alias address can be        found in the cache. If so, a cache hit occurs, the routable        network number of the recipient entity (GK, BE or H.323 endpoint        where the mobile is residing) is obtained from the cache. After        going through the H.323 RAS signaling procedures (the detail is        not discussed for simplicity), the H.323 call is routed to the        recipient entity following steps 4 and 5 described in FIG. 3.        Otherwise, a cache miss occurs, and the next step is executed.    -   Step 2: The originating GK or BE queries the AAP database        following steps 2 and 3 in FIG. 3. After the GK or BE receives        the routable network number of the recipient entity from the        AAR, an entry in the cache is created to store the ported alias        number and the corresponding network routable number.    -   Step 3: The H.323 call is routed to the recipient entity        following steps 4 and 5 described in FIG. 3.        A cache policy may be formulated by determining which criteria        to use to cache an alias address and the associated routable        network number. If the cache is full and the GK or BE wants to        add a new cache, the cache policy may determine which cache is        to be replaced.

The H.323 user mobility scheme requires that the alias addresses need tobe portable. The same alias addresses will be used by users as they movefrom one place to another. The scenarios described earlier show thatproblems of the user, service, and service provider mobility areinterrelated. Once the H.323 signaling protocol (extensions of RAS andcreation of new signaling messages for the database queries to providebackend services) is enhanced to include all functionalities describedabove will also allow a user to keep the same alias number afterchanging the service providers. Thus, it also serves the purpose of theservice provider mobility.

The H.323-based MIN system may be similar to the traditional PSTN/ISDNintelligent networking (IN) system. The following issues need to beresolved to provide interoperability between the two systems:

-   -   Which alias addresses will be considered for portability first?    -   What specific criteria will be used for the alias address        portability (portable vs. nonportable)?    -   How centralized databases vs. distributed databases selected?    -   How is synchronization maintained in the case of distributed        databases?    -   Are new signaling messages generated to define backend services?        Or is it possible to extend the existing message?        H.323 user, service, and service provider mobility can be        provided by requiring that the alias addresses are portable. The        proposed architecture and protocol shows how the H.323 MIN        offers flexibility for alias addresses portability. User,        service, and service provider mobility may be provided based on        the following:    -   The probable alias addresses that can be ported are E.164, IMEI,        IMSI, TMSI, URL-ID, EmailID, Party Number, and Personal ID.    -   There should be a mechanism to differentiate between ported and        non-ported alias address for each alias address type.    -   The ported alias address needs to be mapped to a network        routable address. The mapping can be done using database methods        and cache approaches.    -   The database method can be centralized as well as distributive.        In each case, there are issues that affect the users, services,        and service providers. In nationwide or worldwide implementation        of the databases, it requires to determine how the databases        should be maintained: Individual Service Provider vs. Third        Party.    -   In the case of the distributive implementation, the protocol        that will be used for communications between the administrative        domains needs to satisfy the service providers' requirements as        described in this contribution.    -   In the case of the cache approach method, the policy for cache        maintenance should be standardized considering the buffer size.    -   H.323 protocol (e.g., RAS) needs to extended to accommodate the        needs for triggering the database queries for determining the        ported alias address and mapping the ported alias address to a        routable network address as described in this contribution. If        necessary, the H.323 backend services protocol needs to be        developed in conjunction with the extension of RAS.    -   The mobility management of the terminals, users, services, and        service providers should be implemented as is known in the art.        For example, as the users roam from one place to another, they        need to register in the new location as is known in the art to        receive the services using the ported alias addresses.    -   The interworking between the H.323-based MIN proposed in this        contribution and the traditional PSTN/ISDN IN needs to be        defined.

The present invention provides an overall architecture and overview ofthe protocol for the user, service, and service provider mobilityprimarily in the context of inter-domain communications although thesame principles can also be used for intra-domain or inter-zonecommunications. The example also shows all media (e.g., audio, video,and data) as if they are following the same path from their source anddestination. As a result, it is as if all media have also followed thesame address portability as shown in those examples. However, it is alsopossible that each of the media may follow a different path through thenetwork although they have the same source and destination addresses(e.g., E.164 addresses). For example, audio, video and data mayoriginate from the same source address and can reach the samedestination address, but the real-time audio and video may follow thesame path for maintaining the stringent performance constraint, whilethe path for data traffic through the network may be different from thatof the audio and video. There may be several reasons why the path forthe data traffic will be different: 1. Data traffic may be handled by adifferent network or service provider from that of the audio/video, and2. Data traffic may be offered a different QoS from that of theaudio/video, although the services may be offered by the same network orservice provider. Keeping the same source and destination address, theintermediate addresses of the data traffic may be different. In thisscenario, it is quite possible to have address portability for theintermediate address(es) of the data traffic considering: 1. Either asingle or multiple service providers, 2. Either single or multiplezones, and/or 3. Either a single or multiple domains.

The proposed architecture also complements the terminal mobilityarchitecture, which is known. Although the present invention has beendescribed in relation to particular preferred embodiments thereof, manyvariations, equivalents, modifications and other uses will becomeapparent to those skilled in the art. It is preferred, therefore, thatthe present invention be limited not by the specific disclosure herein,but only by the appended claims.

1. A method comprising the activities of: via a first routable addressof a first H.323 entity, placing a call between the first H.323 entityand a second H.323 entity, the call an H.323 multimedia communicationbetween the first H.323 entity and the second H.323 entity, the firstroutable address obtained via a conversion of an alias address of thefirst H.323 entity, the alias address kept fixed as the first H.323entity moves from a first domain to a second domain; responsive to thefirst routable address, routing an audio portion of the call via a firstnetwork path associated with a first quality of service associated withthe second H.323 entity; and routing a data portion of the call via asecond network path associated with a second quality of serviceassociated with the second H.323 entity.
 2. The method of claim 1,further comprising: at a non-gatekeeper database, receiving, from athird domain, information indicative that the first H.323 entity islocated in the third domain, the first H.323 entity registered in avisiting zone of a gatekeeper database of the third domain.
 3. Themethod of claim 1, further comprising: at a non-gatekeeper database,receiving, from a third domain, information indicative that the firstH.323 entity is located in the third domain, the first H.323 entityregistered in a visiting zone of a gatekeeper database of the thirddomain; and registering the first H.323 entity to receive incoming callsin the third domain via the alias address.
 4. The method of claim 1,further comprising: at a non-gatekeeper database, receiving, from athird domain, information indicative that the first H.323 entity islocated in the third domain, the first H.323 entity registered in avisiting zone of a gatekeeper database of the third domain; andcommunicating a location of the first H.323 entity in the third domainto a database.
 5. The method of claim 1, further comprising: at anon-gatekeeper database, receiving, from a third domain, informationindicative that the first H.323 entity is located in the third domain,the first H.323 entity registered in a visiting zone of a gatekeeperdatabase of the third domain, wherein the first H.323 entity uses adifferent terminal in the third domain than the first H.323 entity usesin the first domain.
 6. The method of claim 1, further comprising: at anon-gatekeeper database, receiving, from a third domain, informationindicative that the first H.323 entity is located in the third domain,the first H.323 entity registered in a visiting zone of a gatekeeperdatabase of the third domain, wherein the first H.323 entity uses adifferent terminal type in the third domain than the first H.323 entityuses in the first domain.
 7. The method of claim 1, further comprising:receiving a request from the second H.323 entity to place the call tothe first H.323 entity, the request comprising the alias address for thefirst H.323 entity; and querying a non-gatekeeper database to obtain acurrent location of the first H.323 entity; mapping the alias address tothe first routable address for the first H.323 entity via thenon-gatekeeper database; communicating the first routable address forthe first H.323 entity to the second H.323 entity; and establishing thecall between the first H.323 entity and the second H.323 entity.
 8. Themethod of claim 1, further comprising: receiving a request from thesecond H.323 entity to place the call to the first H.323 entity, therequest comprising the alias address for the first H.323 entity; andquerying a non-gatekeeper database to obtain a current location of thefirst H.323 entity; mapping the alias address to the first routableaddress for the first H.323 entity via the non-gatekeeper database; andproviding the first routable address to a cache at a gatekeeper, whereinthe gatekeeper removes a second routable address associated with a thirdH.323 entity responsive to a cache policy.
 9. The method of claim 1,further comprising: receiving a request from the second H.323 entity toplace the call to the first H.323 entity, the request comprising thealias address for the first H.323 entity; querying a non-gatekeeperdatabase to obtain a current location of the first H.323 entity; andproviding a billing rate for the call to the second H.323 entity. 10.The method of claim 1, further comprising: determining servicesavailable to the first H.323 entity based upon subscription informationassociated with the first H.323 entity.
 11. The method of claim 1,further comprising: at a non-gatekeeper database, receiving from a thirddomain information indicative that the first H.323 entity is located inthe third domain, the first H.323 entity registered in a visiting zoneof a gatekeeper of the third domain; and obtaining a same servicesubscribed to by the first H.323 entity in the first domain while in thethird domain.
 12. The method of claim 1, further comprising: at anon-gatekeeper database, receiving, from a third domain, informationindicative that the first H.323 entity is located in the third domain,the first H.323 entity registered in a visiting zone of a gatekeeper ofthe third domain; and registering the first H.323 entity to receiveincoming calls in the third domain.
 13. The method of claim 1, furthercomprising: sending a query message with the alias address to a homegatekeeper of a zone comprised by the first domain to determineportability of the alias address.
 14. The method of claim 1, furthercomprising: synchronizing a non-gatekeeper database with at least oneother network database, the non-gatekeeper database configured toconvert the alias address to the first routable address.
 15. The methodof claim 1, wherein the call is a multi-point to multi-pointcommunication.
 16. The method of claim 1, wherein the first routableaddress is received at a first non-gatekeeper database external to thefirst domain and external to the second domain, the first routableaddress received at a second non-gatekeeper database external to thefirst domain and external to the second domain, the first H.323 entityregistered in a home zone of a first gatekeeper database in the firstdomain.